I just found this useful and comprehensive table of how different rubbers are effected by different chemicals http://mykin.com/rubber-chemical-resistance-chart-3 It says that Nitrile rubber is OK with glycol.... but as the auto brake fluid absorbs water over time it must adversely effect the Nitrile O rings as Nigel says. With Nigel's experience in hydraulics I would take what he says as being the most practically accurate. I have always bought genuine Cleveland nitrile rubber 0-rings for the the H36 brake system and used the mineral oil that is recommended for them. You need to pump a lot through to get the bubbles out so the mineral oil saves a fair bit of cash. You can use Automatic Transmission Fluid. Sounds like Glycol based fluids may be OK but on the condition that you need to change them regularly if you have genuine Cleveland seals. And make sure no one gets them mixed up when topping up the system! Rob
regards Rob Rob Thompson 0429 493 828 (Please note that my new email address is [email protected]) On Sun, Jun 24, 2018 at 10:05 PM, Nigel Baker <[email protected]> wrote: > I think your right on the DOT 5 Konrad. Silicone lubricants are fine on BN > seals and Silicone Grease is used to lube BN seals in food processing > machinery as it is non toxic so compatible. > > The H36 mm does say DOT fluid but either some have been changed over at > some stage eg by the Thai Airforce and others or depends on when it was > built. There is a mix out there that I have seen. > > > > *Characteristics of common braking fluids*[6] > <https://en.wikipedia.org/wiki/Brake_fluid#cite_note-DOT-6>[5] > <https://en.wikipedia.org/wiki/Brake_fluid#cite_note-epic-5> > > *Dry boiling point <https://en.wikipedia.org/wiki/Boiling_point>* > > *Wet boiling point* > > *Viscosity limit* > > *Primary constituent* > > DOT 2 > <https://en.wikipedia.org/w/index.php?title=DOT_2&action=edit&redlink=1> > > 190 °C (374 °F) > > 140 °C (284 °F) > > ? > > castor oil/alcohol > > DOT 3 <https://en.wikipedia.org/wiki/DOT_3> > > 205 °C (401 °F) > > 140 °C (284 °F) > > 1500 mm2/s > > glycol ether <https://en.wikipedia.org/wiki/Glycol_ethers> > > DOT 4 <https://en.wikipedia.org/wiki/DOT_4> > > 230 °C (446 °F) > > 155 °C (311 °F) > > 1800 mm2/s > > glycol ether/borate ester > <https://en.wikipedia.org/wiki/Borate#Borate_esters> > > LHM+ > <https://en.wikipedia.org/wiki/Hydropneumatic_suspension#LHS_versus_LHM> > > 249 °C (480 °F) > > 249 °C (480 °F) > > 1200 mm2/s [7] <https://en.wikipedia.org/wiki/Brake_fluid#cite_note-7> > > mineral oil > > DOT 5 <https://en.wikipedia.org/wiki/DOT_5> > > 260 °C (500 °F) > > 180 °C (356 °F) > > 900 mm2/s > > silicone > > DOT 5.1 <https://en.wikipedia.org/wiki/DOT_5.1> > > 260 °C (500 °F) > > 180 °C (356 °F) > > 900 mm2/s > > glycol ether/borate ester > > *Wet boiling point defined as 3.7% water by volume.* > > I have just looked up Matco and yep can use DOT 5 but not 5.1 so same with > the other DOT series fluids. Same chemical problem. > > http://www.matcomfg.com/MASTERCYLINDERCAP10MC4X-idv-3835-5.html > > Thus Diamond must change the seals or they get them special order. Same > problem exists with Cleveland. > > > > Cheers. > > Nige. > > > > > > > > *From:* [email protected] <[email protected]> *On > Behalf Of *Konrad FDU > *Sent:* Sunday, June 24, 2018 8:57 PM > *To:* [email protected] > *Subject:* AW: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36 > > > > Hello Rob, > > > > my MM for the Super Dimona specifies DOT4 as break fluid. So does TOST > which also is a Cleveland break. It is not specify DOT 5 that you might > refer to and is silicone based (not DOT5.1 which again is glycol based) . > > I would not call DOT4 or DOT3 water soluble. It is hygroscopic and accepts > to accumulate the humidity from the air but water degrades performance and > boiling point. This is why break fluid is changed regularly or checked for > water. > > > > regards > > Konrad > > > ------------------------------ > > *Von:* [email protected] [mailto:[email protected] > <[email protected]>] *Im Auftrag von *Rob Thompson > *Gesendet:* Sonntag, 24. Juni 2018 11:59 > *An:* [email protected] > *Betreff:* Re: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36 > > Hi Michael, > > So you have been running water soluble auto fluid in Cleveland brakes for > 17 years? > > Interesting. I didn't think the rubber bits would go OK with a > water/glycol based fluid. > > Make sure you label the reservoir very clearly what type you are using. If > someone adds the wrong type you will get a horrible mess! > > > regards > > Rob > > > > Rob Thompson > > 0429 493 828 > > (Please note that my new email address is [email protected]) > > > > On Sun, Jun 24, 2018 at 9:26 AM, Michael Stockhill <[email protected]> > wrote: > > I believe the service manual specifies automotive type fluid, likely for > the motorcycle type master cylinder. No problem with Cleveland O rings in > slaves for last 17 years. > > > > Best > > > > Michael Stockhill > > > > > > > > > > > > On Jun 23, 2018 3:01 PM, "Rob Thompson" <[email protected]> wrote: > > Just a reminder to everyone and Martin from K1W1 land. > > The H36 uses hydraulic brake fluid. Auto fluid is water based and will > wreck the seals and system. > > > > regards > > Rob > > > > Rob Thompson > > 0429 493 828 > > (Please note that my new email address is [email protected]) > > > > >
